1. Field of the Invention
The present invention relates generally to polyimides which are suitable for high temperature applications as a result of their high or nondetectable glass transition temperatures and their high thermooxidative stabilities. It relates particularly to three types of polyimides which are prepared from monomers containing carbon-carbon double and/or triple bonds, in particular N-(3-ethynylphenyl)maleimide (NEPMI).
2. Description of Related Art
Polymers prepared from the reaction of organic compounds containing pendant ethynyl groups or organic oligomers containing pendant ethynyl groups are well known for their thermooxidative stability and exceptionally high glass transition temperatures. Likewise, organic compounds or oligomers containing activated carbon-carbon double bonds and imide moieties (i.e. maleimides) can be used to prepare thermally stable polymers.
Hergenrother et al. (U.S. Pat. No. 4,889,912 and U.S. Pat. No. 4,937,356) prepared acetylene terminated aspartimides by reacting an aromatic diamine with NEPMI. These acetylene terminated aspartimides were blended with acetylene terminated polyarylene ethers or sulfone oligomers to yield polymers with improved mechanical properties such as fracture toughness.
Hergenrother et al. (U.S. Pat. No. 4,861,882) also prepared ethynyl terminated imidothioethers by reacting a dimercaptan with NEPMI. These ethynyl terminated imidothioethers were then blended with other ethynyl terminated oligomers to produce resin blends which are useful as adhesives, coatings, and films. The glass transition temperatures of these blends ranged from 193.degree.-245.degree. C.